Question

I have the statement below when creating a Oracle view. The statement is to return a particular value as MYVALUE column.

(SELECT myval 
  FROM (SELECT myval 
          FROM mytable 
         WHERE primary_key = /*CS.primary_key*/ 12345 
         ORDER BY table_primary_key ASC) 
 WHERE ROWNUM < 2) AS MYVALUE,

The inner query can return more than one row. I am only interested in the 1st record and it must be ordered by the table_primary_key, hence the use of the sub query to allow the ROWNUM selection.

When I create the query in its current state above, the view is created successfully. When I uncomment CS.primary_key and remove the hardcoded 12345, the view creation fails, with no description of why

(SQLDeveloper 2.1): “Failed: Warning: execution completed with warning”.

Also, just to try and narrow down the problem, I removed the ORDER BY, and ROWNUM as below, and the same error occurs

(SELECT myval 
  FROM (SELECT myval 
          FROM mytable 
         WHERE primary_key = CS.primary_key) 
) AS MYVALUE,

Lastly, I know CS.primary_key is a valid reference, as I use in in other parts of my view without issues.

Any idea why the reference is valid, or how to get a more detailed error message?

edit: updated starting opening bracket

EDIT2: Thanks for the responses so far. Here is a summary of the problem, I think the CS.PRIMARY key should be in scope, as I use it in other places in my query. The code below works, but if I replace the hardcoded 1 to CS.primary_key, it fails:

drop view myview;
drop table mytable;
drop table mytable_parent;
drop table proof_table;

-- ISSUE TABLES
create table mytable_parent ( primary_key number primary key );
create table mytable ( primary_key number, myval varchar(255), parent_primary_key number);
insert into mytable_parent values (1);
insert into mytable_parent values (2);
insert into mytable values (1, 'myval1-1', 1);
insert into mytable values (2, 'myval1-2', 1);
insert into mytable values (3, 'myval2-1', 2);

-- EXAMPLE TABLE TO PROVE CS.* WORKS
create table proof_table ( primary_key number primary key, parent_primary_key number, any_old_value varchar(255));
insert into proof_table values (1, 1, 'proofval1-1');
insert into proof_table values (2, 2, 'proofval1-2');

-- VIEW
CREATE OR REPLACE FORCE VIEW myview AS 
  SELECT 

  -- PROOF STATEMENT USING CS.primary_key SUCCESSFULLY
  (SELECT any_old_value FROM proof_table WHERE parent_primary_key IN 
    (SELECT primary_key FROM proof_table WHERE parent_primary_key = 

    -- USING CS REFERENCE, NO PROBLEM
    CS.primary_key)

  ) AS PROOF_VALUE,

  -- PROBLEM STATEMENT
  (SELECT myval FROM (SELECT myval FROM mytable 
         WHERE parent_primary_key = /*CS.primary_key*/ 1
         ORDER BY primary_key ASC) 
  WHERE ROWNUM < 2) AS MYVALUE  

  -- DEFINE CS
  FROM mytable_parent CS;

Answer 1

From the limited information you have supplied I’d suggest that CS.PRIMARY_KEY is out of scope for your subquery. Hence it compiles OK when you use a literal and doesn’t compile when it has to resolve the reference to CS.PRIMARY_KEY.

Include whichever table CS refers to in the subquery (with the relevent criteria) to check that this is the case.
If it is then you’ll need to rewrite your query to ensure the CS table is in scope for all its dependencies.

Hope it helps…

See the details in this link: http://etutorials.org/SQL/Mastering+Oracle+SQL/Chapter+5.+Subqueries/5.4+Inline+Views/

You will see that inline views are executed prior to the outer query and nesting the reference to the CS table too deeply will cause it to become out of scope.

Replace the nested subquery where you do your ordering:

(SELECT myval 
   FROM (SELECT myval 
           FROM mytable
          WHERE parent_primary_key = CS.primary_key
          ORDER BY primary_key ASC)
   WHERE ROWNUM < 2) AS MYVALUE

with an analytic function or other way of limiting your rows and it will work fine

This is untested but replacing the above code with:

(SELECT DISTINCT 
        FIRST_VALUE(myval) OVER (PARTITION BY parent_primary_key ORDER BY primary_key) 
   FROM mytable
  WHERE parent_primary_key = CS.primary_key) AS MYVALUE 

might be close to what you want and the reference to CS is in scope.